Well, I guess the topic says it allI've tried to google the question, but without any luck.Maybe some of you got the pratical experience

Hi,

Welcome to the forum!

Do you have one in a Sys - II? As long as nothing sticks up higher than the Systainer bottom side walls , then it will fit under the attic lid. The attic lid is completely within the Systainer top. The attic is equal to the depth of the Systainer lid.